Figure 4 Chromosomal profiles of commercial wine yeast strains analyzed in Fernandez-Espinar et al. (2001).
Using mtDNA restriction patterns, Querol et al. (1992a) conducted the first study of population dynamics and the roles played by the active dry yeast strain and the natural Saccharomyces flora during inoculated industrial fermentations. It was demonstrated that the inoculated strains T73 (Lallemand) compete with the natural strains but do not completely suppress their growth until three to six days after inoculation. However, the predominance of the inoculated strain was evident at the end of the fermentations.
Using physiological tests and karyotyping, Schutz and Gafner (1993) analyzed the succession of three different dried yeasts at three different time points of wine fermentation. Hanseniaspora uvarum was present at the beginning of the fermentation, whereas only the inoculated strains of S. cerevisiae were observed in the middle and at the end of the fermentation. However, as a consequence of the few strains, these authors did not detect as much diversity as that observed by Querol et al. (1992a).
The use of active dry yeasts is of particular interest for the wine industry. It is generally assumed, as we discussed previously, that indigenous yeasts are suppressed by the starter. However, some studies showed that native strains are better adapted to fermentation conditions than commercial strains (Esteve-Zarzoso et al. 2000; Esteve-Zarzoso and Peris-Toran 2001).
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